Wrocław: high precision GNSS tracks

I’m creating GPX tracks near Wrocław, because some of villages have no any track available to check satellite imagery offset.

I found that Wrocław has a station LEICA GR50 from ASG by EUPOS: http://www.asgeupos.pl/index.php?wpg_type=syst_descr&sub=ref_st

How can I use the signal of this station to create high quality GPX tracks?

Should I use any of RTKLIB-compatible GPS devices?

Note that in Poland geoportal.gov.pl aerial imagery is so good that it can be used to align other aerial imagery.

Sadly I have no idea at all here :frowning:

ASG-EUPOS is now a paid service. It was free only in the beginning.

Sad. I need accurate GNSS tracks not for checking satellite imagery offset only, but also for example to create good quality image sequences for Mapillary.

So, as an alternatives:

  1. Buy device with multiband GNSS (L1 + L5 GPS)

  2. Buy some RTK kit (SparkFun / u-blox ?), create own station and share diff into internet.

  3. Buy temporary access from, for example, https://www.tpinet.pl/kup-dostep

First step looks good. Anyway I need more accurate GNSS to work with RTK.

Any other idea?

I’ve ordered from digikey.pl:

  • SparkFun GPS-RTK-SMA ZED-F9P BREAKOUT — board with u-blox ZED-F9P

  • U-Blox ANN-MB-00-00 — active antenna, IP67

But there was no metal ground plane which is highly recommended by u-blox. I hope, any piece of metal will be fine for this.

My precious arrived!

I had to pay import tax 290 PLN in addition to shop price 1170 PLN…

That’s quite a lot of money.
Do you know of any cheap standalone L1+L2 receivers? In open sky conditions they are pretty good, as tested by some Xiaomi phone users on our FB group.
But I don’t want to buy a phone just to record tracks. :smiley:

I don’t know.

I saw some cheap “multiband” modules on aliexpress, but I don’t believe they are really multiband. I think it is better to take some old used u-blox NEO-M8* / NEO-M9* modules than to buy fake “multiband” module with unknown precision. As I understand, it is better to use L1 receiver with correction than multiband receiver without correction data.

You can take a look at https://rtklibexplorer.wordpress.com , he is “exploring precision GPS/GNSS with RTKLIB open source software and low-cost u-blox GNSS receivers”.

Also you can take my module when you need it. I’m in Wrocław :slight_smile:

People I know on OSM using RTK include Jean-Guilhem Caiton (jgc) with ublox modules in France & in the UK both Russss and Firefishy have recently acquired them. There’s also a thread in this forum in Russian on RTK. It’s possible that sharing experience & advice would be useful. I felt that perhaps this was something a national association could invest in: however, in the UK we now have accurate open data on cadastral parcels which fulfills the purpose of high-quality image alignment.

I used a US 1 gallon paint can lid as the ground plane. It is very close to the recommended size.

I’m using something similar, thank you!

I solved problem with GPSBabel: https://help.openstreetmap.org/questions/79521/filter-out-gnss-trackpoints-by-radius
So now I have a script to convert all NMEA files into one GPX and filter them to remove some noise.

I’m satisfied with a quality of tracks even without correction. Maybe I will not use a correction, because wrong correction can create a align for all tracks (am I right in this?).

My current setup:

  • Receiver SparkFun GPS-RTK-SMA ZED-F9P

  • IP67 active antenna: U-Blox ANN-MB-00-00, with 5 meters cable…

  • Single board computer: i.MX53 Quick Start board (1 GB RAM), it uses 5V x 0.3-0.5A when running

  • Noname powerbank with 3x18650 and controller TPOWER TP4366

  • Rainproof bag https://www.sportarsenal.cz/brasny/art–310/

Ta-da! Here are the tracks: https://www.openstreetmap.org/user/Alexey%20Vazhnov/traces/tag/u-blox%20zed-f9p

Started a wiki-page: https://wiki.openstreetmap.org/wiki/User:Vazhnov_Alexey/Record_GNSS_traces


  • Better metal ground plane

  • Current setup spends whole bag, I need to make it more compact

  • Better power supply: my SBC can eat more than 1A when initializing, and my powerbank switches off sometimes on start

  • Replace SBC with a simple logger

  • Add Bluetooth to have connection with Android smartphone


The Polish state NTRIP caster costs money for live RTK, but for the subsequent correction of the tracks at the PC at home you can download the correction data (RINEX files?) of the stations for free!

In addition, there are many private people (farmers?) who operate similar fixed stations for live RTK for free (http://rtk2go.com/ or, for Poland could also work, then you don’t see the extremely long list of all data streams in the world but only the Polish ones).

Spartaner, this is that I need! Thank you very much! I will try to create new GPX tracks with correction for OSM.

With system.asgeupos.pl feature “send files”, I’ve got an error because it allows only RINEX format in version 2.x. Currently I have only RINEX 3.

I’ve successfully connected with rtk2go.com, thank you!

I’m stuck with rnx2rtkp error “no nav data”: https://github.com/tomojitakasu/RTKLIB/issues/661
Spartaner, maybe you know how to fix it?